An earthquake damage index is used to quantitatively approximate the damage caused by an earthquake to a portfolio of defined objects located in a defined geographical area, such as buildings, bridges, highways, power lines, communication lines, manufacturing plants or power plants based solely on physically measured and publicly available parameters of the earthquake phenomenon itself. An earthquake damage index can be assessed immediately after the earthquake. Defining the earthquake damage index solely on a measured magnitude of the earthquake has the disadvantage that there is no consideration of the portfolio and its geographical distribution of objects. Consequently, an earthquake damage index based solely on the magnitude of the earthquake correlates poorly with the true damage caused to the objects of the portfolio. Particularly, with an increase of the size of the geographical area, the magnitude based damage index shows an increasingly poor correlation with the true damage. Thus other methods use other physical parameters of an earthquake occurrence than magnitude, i.e. earthquake shaking intensity in form of peak ground acceleration or peak ground velocity. Such parameters depict in areas of the world equipped with a dense net of seismograph stations a map of the aerial extent of earthquake shaking intensity rather than only a single point measurement of the magnitude. Combining the aerial extent of earthquake shaking intensity with the distributed portfolio of objects allows for a much better correlation of the thus deducted earthquake damage index with really occurred damages to the portfolio, while not sacrificing the immediateness of applicability after the event as well as transparency to anyone willing to set up the computing procedure. However, owing to the cost of installation and maintenance, an infrastructure with a network of geographically densely distributed seismological measurement stations is currently not available in the majority of countries.